FRONT BRAKES 1050 SPD TRP

[HARTY]

Hi all

I dont have a trp but I do have a share in a dealership in sunny South Africa and we are experiencing problems with the front brakes on the new 1050 trp

After a bit of use they become very soft and non responsive
and there is alot of play on the lever.

bleeding them does not solve the problem

If there have been posts on this issue I am sorry-too many to go through !

Regards

[Martin_R]

This is a known issue. The caliper seals stick too much on the pistons and pull them too much back when you release the lever.

Triumph workaround #1: disassemble calipers pistons & seals and reassemble with greased pistons+seals. I am sure there is a technical bulletin about this for the Triumph dealers as to which grease should be used etc.

Unofficial workaround #1: get a 5/8" replacement master cylinder from Nissin. This will shift the brake feel more towards wooden, so now you have more power, less play and less feel.

Unofficial workaround #2: stop monkeying around and fit better front calipers.

Triumph might also have improved caliper seals or pistons available now? I would think that using coated pistons would cure this problem as the seals would not stick so much.

Do a search on this forum and t595.net and you will find plenty of info on this subject.

[ This message was edited by: Martin_R on 2006-03-15 03:53 ]

[HarriS]

On 2006-03-15 03:52, Martin_R wrote:
Unofficial workaround #1: get a 5/8" replacement master cylinder from Nissin. This will shift the brake feel more towards wooden, so now you have more power, less play and less feel.

More likely less power because there is less hydraulic "leverage" with a bigger master cylinder. You have to pull the lever harder to get the same hydraulic pressure at the caliber.

[Martin_R]

On 2006-03-15 04:26, HarriS wrote:
More likely less power because there is less hydraulic "leverage" with a bigger master cylinder. You have to pull the lever harder to get the same hydraulic pressure at the caliber.

? Now I am unable to follow your thought.

If you have a bigger chamber full of fluid and cram this larger amount of fluid down the same tube as before you will end up with more fluid at the brake calipers with the same amount of lever travel
-> the brakes will lock earlier and feel harder as the range of motion needed on the lever is less than before
-> more braking power for the same amount of movement on the lever

Or did you just mean that because you are moving more fluid you will have to apply more pressure on the lever in order to get the same amount of lever travel? This is true of course. Barely noticeable though.

More noticeable is the shorter range of motion needed for full on braking. The brakes are firmly locked with a 1/2 pull on the lever with the lever in the closest setting (1?). Granted I have quite new pads also.

[HARTY]

Thanks guys

Harris , the lever on these bikes can not be pulled any harder .the lever touches the bar . No adjustment helps .

[6485]

Harty, take the calipers off, and pry in between the pads with a screwdriver or something, pushing the pistons back in. I read this on another post and didn't really think it would work, but when I put a new front tire on, I did this and the difference in feel was unbelievable! Over time, the mushiness will probably come back, this is just a temporary fix.

[littlefield]

On 2006-03-15 04:45, Martin_R wrote:

? Now I am unable to follow your thought.

If you have a bigger chamber full of fluid and cram this larger amount of fluid down the same tube as before you will end up with more fluid at the brake calipers with the same amount of lever travel
-> the brakes will lock earlier and feel harder as the range of motion needed on the lever is less than before
-> more braking power for the same amount of movement on the lever

Or did you just mean that because you are moving more fluid you will have to apply more pressure on the lever in order to get the same amount of lever travel? This is true of course. Barely noticeable though.

More noticeable is the shorter range of motion needed for full on braking. The brakes are firmly locked with a 1/2 pull on the lever with the lever in the closest setting (1?). Granted I have quite new pads also.

The 5/8 inch (about 16 mm) cylinder moves about 30% more fluid to the caliper than the stock 14 mm unit for a given amount of movement on the lever. But because the force on the lever is distributed over a larger area in the cylinder you get about 30% less pressure. So the caliper moves and contacts the rotor with less lever travel but takes more force on the lever for a given load on the brakes. It's a 'you don't get something for nothing' deal.

[HarriS]

Exactly. The force that binds the disc is pressure * area of the caliber pistons. The static pressure of the hydraulic brake system is the same everywhere in the fluid. The bigger main cylinder has larger area than before so you have to apply more force to get the same hydraulic pressure per square millimeter.

And if you compensate this by adding more mechanical leverage at the brake lever, you end up right where you started.

[ This message was edited by: HarriS on 2006-03-15 08:23 ]

[kuhlka]

I installed a 5/8 MC and haven't noticed what you guys are talking about, so it must be a negligible change in force. Hell, I even have shorty levers and only use two fingers for braking AND stoppies. Maybe you pansies just need stronger fingers and better bleeding skills. My brakes don't go to ***** until my pads need to be replaced, and even then I can still pump the brakes up to get feel again.

My recommendations for your 05+ S3 issue is doing the caliper rebuild as mentioned on t595 and here, and start stocking the 5/8 nissin master cylinders and double H brake pads for customers to buy when they want a little extra umph. With those changes, the brakes should stop like a SOB and stoppie on demand.

[kuhlka]

Oh, the 'pushing the pistons back into the calipers' aka 'exercising the pistons' as well as pumping the brake lever and/or zip-tying it overnight are just temporary fixes.

The more sure-fire fix I've heard of is that rebuild kit. I'll try and find the info and repost it.

I find my local motorcycle shop does a pretty half-ass job of bleeding brakes, so I always go back in and rebleed thoroughly using both the vacuum pump and bottle to get every last little bit of air out of the lines.